阿克曼菌对鲤糖代谢的调控作用研究

[目的]本试验旨在探究巴氏灭活的阿克曼菌（Pasteurized Akkermansia muciniphila，P-Akk）调控鲤（Cyprinus carpio L.）糖代谢的分子机制。[方法]本研究通过不同糖水平（20%、30%、40%、50%葡萄糖）试验，探究鲤（10.5±1 g）4周和8周时胰高血糖素样肽-1（glucagon-like peptide-1，GLP-1）分泌及阿克曼菌（Akkermansia muciniphila，Akk）定植的时空变化；在不同糖水平试验基础上，设置40%葡萄糖和三个不同浓度P-Akk（108 cfu/g P-Akk、109 cfu/g P-Akk、1010 cfu/g P-Akk）组，探究添加P-Akk 4周后对鲤（16.38±0.39 g）糖代谢及GLP-1的调控；通过P-Akk孵育鲤原代肝、肠细胞试验，共同探究不同糖水平下鲤肠道Akk、GLP-1对糖代谢的调控机制。[结果]结果显示：（1）随着饲料中葡萄糖含量的升高，鲤血清中GLP-1b含量显著降低（P < 0.05），4周时高糖组鲤肠道GLP-1a、GLP-1b以及肠道内容物中Akk丰度均显著降低（P < 0.05），但8周时无显著性差异（P > 0.05）。（2）P-Akk处理后，鲤血清中葡萄糖、GLP-1含量显著减少（P < 0.05）；中肠绒毛高度、肌层厚度显著增加，GLP-1含量减少，短链脂肪酸含量增加，muc2 mRNA表达水平升高（P < 0.05）；此外，P-Akk上调肝脏中ampk、pi3k、akt及糖酵解基因gk、pfk mRNA表达量，下调糖异生基因pepck mRNA表达量（P < 0.05）。（3）原代肝、肠细胞孵育结果显示，P-Akk处理肠细胞后GLP-1含量显著减少（P < 0.05），而gpr40的mRNA表达量升高；此外肝细胞中糖酵解基因gk、pfk mRNA表达量显著升高。[结论]综上，外源添加P-Akk可以缓解高糖饲料引起的血糖升高，维持葡萄糖稳态。[意义]该研究结果可为Akk作为益生菌在水产饲料中的应用提供理论基础。     

钾肥水平对油茶果实性状及产量的影响

为了研究钾素水平对油茶果实性状和产量的影响及它们之间的关系,设置了6个不同钾肥用量处理,以8年生的长林53号和长林27号两个油茶无性系为试材在江西永丰开展了施肥试验,连续两年测定了油茶果径、单果质量、干出籽率、干出仁率、种仁含油率、鲜果含油率、单株结果数、单株果实产量和产油量等指标,比较和分析了不同无性系的不同处理之间的差异。结果表明,两个无性系的果实性状和产量对钾肥水平差异的响应均存在大小年差异;结实大年时,钾肥水平对两个无性系果实的果径、单果质量和干出仁率影响不大,对其他性状的影响均达到显著水平;结实小年时,钾肥水平仅对53号无性系单株结实数量和产量造成影响且无明显梯度规律,而27号无性系随着钾肥水平的提高,其干出籽率和鲜果含油率呈先上升后下降趋势,单株果实数量、产量和产油量则呈下降趋势;无论大年还是小年,单株产量均与结实数量关系最密切,大年的产量在油茶生产中占据主导地位,就大小年平均产量而言,两品系均以中等钾肥水平的K2和K3处理最优。适量增施钾肥可有效改善油茶结实大年果实性状,提高单株结实数量,实现增产增效。     

不同蛋白质水平饲粮对大巴沙三元杂种猪生长性能和胴体品质的影响

为研究不同蛋白质水平饲粮对大巴沙猪生长性能、胴体品质和肉质的影响,选择体重25 kg左右的大巴沙三元杂种猪36头,随机分成3组,每组2个重复,每个重复6头,公母比例一致。试验分前期(25~60 kg)和后期(60~100 kg)2个阶段。高蛋白质组前期和后期蛋白质水平分别为16.00%和14.02%,中蛋白质组分别为15.00%和13.02%,低蛋白质组为14.00%和12.02%。结果表明,与中蛋白质组、低蛋白质组相比,高蛋白质组全期日增重分别提高5.47%(P0.05)和10.31%(P0.05),全期料重比分别降低3.28%(P0.05)和11.72%(P0.05);3点平均背膘厚分别提高0.56cm(P0.01)和0.29 cm(P0.05);眼肌面积分别提高7.85%和降低3.45%;整个试验期每千克增重成本分别降低0.23元和1.05元。综合考虑,大巴沙三元杂种猪饲粮适宜的粗蛋白质水平为前期15.00%~16.00%、后期13.02%~14.02%。     

Source–sink relations and responses to sink–source manipulations during grain filling in wheat

The source–sink ratio during grain filling is a critical factor that affects crop yield in wheat, and the main objective of this study was to determine the source–sink relations at both the canopy scale and the individual culm level under two nitrogen (N) levels at the post-jointing stage.  Nine widely-used cultivars were chosen for analyzing source–sink relations in southwestern China; and three typical cultivars of different plant types were subjected to artificial manipulation of the grain-filling source–sink ratio to supplement crop growth measurements.  A field experiment was conducted over two consecutive seasons under two N rates (N+, 150 kg ha^–1; N–, 60 kg ha^–1), and three manipulations were imposed after anthesis: control (Ct), removal of flag and penultimate leaves (Lr) and removal of spikelets on one side of each spike (Sr).  The results showed that the single grain weights in the three cultivars were significantly decreased by Lr and increased by Sr, which demonstrated that wheat grain yield potential seems more source-limited than sink-limited during grain filling, but the source–sink balance was obviously changed by climatic variations and N deficient environments.  Grain yield was highly associated with sink capacity (SICA), grain number, biomass, SPAD values, and leaf area index during grain filling, indicating a higher degree of source limitation with an increase in sink capacity.  Therefore, source limitation should be taken into account by breeders when SICA is increased, especially under non-limiting conditions.  Chuanmai 104, a half-compact type with a mid-sized spike and a long narrow upper leaf, showed relatively better performance in source–sink relations.  Since this cultivar showed the characteristics of a lower reduction in grain weight after Lr, a larger increase after Sr, and a lower reduction in post-anthesis dry matter accumulation, then the greater current photosynthesis during grain filling contributed to the grain after source and sink manipulation.      

Pubertal development of male African catfish,Clarias gariepinus. In vitro steroidogenesis by testis and interrenal tissue and plasma levels of sexual steroids

In fish, sex steroids initiate and/or accelerate the maturation of the brain-pituitary-gonad axis. In order to obtain information on the steroid milieu during the pubertal development of male African catfish, we have monitored the conversion of [³H]-pregnenolone and [³H]-androstenedione by testis and [³H]-pregnenolone by interrenal tissue fragmentsin vitro. Pubertal development occurs between two and six months of age. Testicular development proceeds through four main stages that are characterised histologically by the presence of spermatogonia (stage I), spermatogonia and spermatocytes (stage II), spermatogonia, spermatocytes and spermatids (stage III), and all germ cells including spermatozoa (stage IV). 11β-Hydroxyandrostenedione and cortisol were the main products of testes and interrenal tissue, respectively, in all stages of the pubertal development; a change in the steroidogenic pattern was not observed during this period. The interrenal tissue displayed no significant conversion of [³H]-pregnenolone to 11-oxygenated androgens. Blood plasma was analyzed for the presence of five androgens; testosterone, 11β-hydroxytestosterone, 11β-hydroxyandrostenedione, androstenetrione, and 11-ketotestosterone. 11-Ketotestosterone was the quantitatively dominating androgen in the circulation at all stages of development, which was more pronounced in stages III and IV. The obvious differences between thein vitro andin vivo results, namely 11β-hydroxyandrostenedione being the main testicular productvs. 11-ketotestosterone dominating in the blood, may indicate that 11β-hydroxyandrostenedione is converted to 11-ketotestosterone at extratesticular sites.     

Effect of a size-based selection program on blood metabolites and immune response of Litopenaeus vannamei juveniles fed different dietary carbohydrate levels

Blood metabolites in wild and seventh-generation cultivated shrimp were measured to determine how size-based selection could alter the nutritional and immunological conditions of Litopenaeus vannamei. Wild L. vannamei juveniles and a sample of seventh-generation cultured shrimp were acclimated under identical conditions. During 55 days, shrimp were fed a high (HCHO: 44%) or a low (LCHO: 3%) carbohydrate diet for 55 days. Wild shrimp showed a direct relation between dietary CHO and lactate, protein and hemocyte levels indicating that dietary CHO was used for protein synthesis via transamination pathways. In seventh-generation cultured shrimp these parameters were inversely proportional to dietary CHO level, indicating the capacity to synthesize protein from dietary CHO was repressed in cultured shrimp. Farmed shrimp showed a limited capacity to respond to LCHO diets demonstrating high protein dependence in their metabolism and immune response. These results demonstrate that during size-based breeding programs other metabolic process than CHO catabolism can be selected. The incapacity of shrimp to use dietary CHO could limit protein reduction of diets and limit the efforts of the shrimp industry to be ecologically and environmentally profitable.     

Ion levels in the gastrointestinal tract content and plasma of four teleosts with different feeding habits

The levels of various ions (Na⁺, Cl⁻, Ca²⁺, Mg²⁺, K⁺) in the fluid phase of the gastrointestinal contents and of the plasma were determined in four teleosts with different feeding habits: traira (Hoplias malabaricus), hassar (Hoplosternum littorale), silver catfish (Rhamdia quelen), and grass carp (Ctenopharyngodon idella). The results showed that most ionic levels in the fluid phase of the gastrointestinal tract seem to be affected by feeding habit and that these levels can be different from those found in the plasma. In practical terms, these results suggest that ionic levels of the gastrointestinal contents should be considered when preparing solutions for studies of intestinal absorption in fishes.     

观察饲料添加剂二次蓄积对幼犬性激素水平的影响

本试验旨在研究分析市场上正在广泛使用的饲料添加剂,探讨二次饲喂雄性幼犬后饲料添加剂蓄积对其生长、生殖发育的影响研究。选用12只1月龄犬,随机分为试验组和对照组,对照组犬饲喂正常日粮和大鼠鼠肉,试验组犬饲喂正常日粮和高剂量组大鼠鼠肉,喂养幼犬直至成熟,检测食用饲料添加剂高剂量组大鼠鼠肉是否对雄性犬的生长、生殖发育产生影响。采用酶联免疫试剂盒的方法来检测犬血清激素指标水平。结果显示：试验组雌二醇、促卵泡激素含量明显升高（P＜0.01）,而睾酮含量明显降低,有显著性差异（P＜0.01）,饲料添加剂高剂量组对犬血清中的促黄体生成未见显著变化。雄性幼犬食用试验大鼠后可导致雄性幼犬青春期体内内分泌激素含量异常,即青春期11月龄测定的雌二醇以及促卵泡激素水平增高,睾酮的水平降低。提示试验组雄性幼犬食用大鼠鼠肉后,可能通过干扰了睾丸轴的功能,对雄性幼犬的生殖发育能力产生影响。     

不同施肥水平对水稻沈农9741品质的影响

以沈农9741为材料,探讨了不同施肥水平对其品质的影响。结果表明,氮肥施用量与沈农9741整精米率、蛋白质含量显著相关,氮、磷、钾肥施用量与垩白粒率显著或极显著正相关,氮肥施用量与粒宽和精米白度显著负相关。     

微生物肥料对不同节肥水平下烤烟生长与产质的影响

通过大田随机区组试验研究了10%、20%、30%节肥水平下两种微生物肥料对烤烟生长及产质的影响。结果表明:(1)在团棵期和旺长期,烤烟的农艺性状随着减肥量的增加而降低,在30%节肥水平时,降低较为明显,对烤烟生长的影响较大。到成熟期,金农肥中肥各节肥水平对烤烟的农艺性状均有不同程度的提升,德根贝在10%节肥水平时,烤烟的农艺性状有提升,在20%和30%节肥水平时分别降低10.4%、4.9%。(2)烤烟在3种节肥水平下其经济性状与对照均无显著差异,但不同节肥水平之间存在差异。两种微生物肥料均在20%节肥水平时,烤烟经济性状表现最好。金农肥中肥效果较为明显,显著提高了烤烟上等烟比例、中上等烟比例及均价,且烤烟产值比对照、10%节肥水平、30%节肥水平分别增加12.5%、34.5%、28.2%。